Ammonium nitrate solid composite propellant composition



grains may be subjected in storage.

AMfMONiUM NITRATE SOLID COMPOSITE PROPELLANT COMPOSITION Jack Linsk,Highland, Ind, assignor to Standard Oil "Company, Chicago, 11]., acorporation of Indiana No Drawing. Filed Nov. 8, 1955, Ser. No. 545,789

'12 Claims. (Ci. 52-.5)

This invention pertains to a gas-generating composition consistingessentially of ammonium nitrate as the primary gas-producing componentof the composition, a combustible binder material and a combustioncatalyst. More particularly, the invention relates to a composition inthe form of a shaped grain suitable for use in rocketry by generating agas from a mixture consisting essentially of ammonium nitrate, acombustion catalyst and a combustible binder. Such composition is usefulfor the propulsion of rockets, such as ground-to-ground missiles,ship-to-shore missiles, air-to-air missiles, and airto-ground missiles;for assist take-oft rockets in aircraft and for producing gas at highpressure.

Ammonium nitrate is widely used as a component of high explosives,particularly the so-called safe explo- 'sives. highly explosive it isextremely insensitive to ordinary heating and cannot be readilydetonated by the local ap plication of heat or by a blasting cap andwhen ignited ammonium nitrate alone does not burn and has a tendency togo out. The use of ammonium nitrate for rockets is attractive because ofthe low cost and availability of ammonium nitrate, because of therelatively low flame temperature of the decomposition of the nitrate andbecause of the excess free oxygen available.

Certain physical characteristics of ammonium nitrate and grain materialproduced therefrom introduce pro Even though ammonium nitrate isconsidered as lems with respect to sturdiness of the grains and chemicalstability under high and low temperatures to which the Thus ammoniumnitrate exists in different crystalline forms, and the transition fromone form to a different form involves a volume change of the ammoniumnitrate. Volume changes which occur at about 90 F. and also at about 0F. are particularly destructive to shaped propellant grains.

A solid propellant gas-producing grain for assist takeoff service and inrocket propulsion must meet a great many service requirements. Jetplanes operate from the Arctic region to the Equator and thence to theAntarctic region with service temperatures over this sweep in the rangefrom --70 F. to +140 F. Bases for aircraft, military and commercial, aresituated over this entire range. Rockets, ATO units and gas-generatorsmust be capable of being stored frequently for :months under theseconditions, i.e. the grain must not change with respect to dimensionalconfiguration or develop fissures or cracks.

There should be no operation problems with the ignition of the grainsunder this wide range of atmospheric temperature; and the rate at whichthe gases are generated from the gas-generating composition must besubstantially constant regardless of temperature.

The gas-producing grain must be physically strong. It must be able towithstand the handling in going from the point of manufacture thousandsof miles by train, truck, ship, or aircraft to its final destination.Not only must it withstand rough treatment in its shipping case, but it2,973,255 Patented Feb. 28,

must be capable of withstanding rough handling by nance people.

An object of this invention is a gas-generating composition usingammonium nitrate as a principal gasgenerati-ng material. Another objectof this invention is a gas-generating composition which is ballisticallystable after being subjected to high and low temperature environment.Still another object of the invention is a gasgenerating compositionwhich is relatively stable chemically at temperatures encountered instorage. A further object of the invention is a gas-generatingpropellant composition which is capable of being shaped into combustiblegrains, which grains exhibit good ballistic performance followingstorage at high temperature and following mechanical shock in thehandling of said grains. Other objects will be apparent in the detaileddescription of the invention.

The composition of this invention consists, on a weight basis of:

(1) About 15% to about 25% of a binder which consists essentially of, ona weight basis, of

(a) About 20% to about 40% of cellulose acetate polymeric materialcontaining from about 51 to about 57% acetic acid, I

(b) About 10% to about 30% of dinitrotoluene, (0) About 10% to about 30%of a component selected from the class consisting ofdinitrophenoxyethanol and mixtures of dinitrophenoxyethanol withbis(dinitrophenoxy)ethane which mixtures contain at least 50% by weightof dinitrophenoxyethanol,

(.d) About 25% to about 40% of ethylene glycol diglycolate, and (2) Acombustion catalyst in an amount suflicient to promote combustion ofsaid composition, and

(3) The remainder essentially ammonium nitrate. There may be included inthe above composition from about 0.3 to about 2% by weight of finelydivided carbon; from about 0.2 to 2% of an organic amine and a minoramount, e.g. of about 0.1%, of a surfactant. I

The binder of the composition consists essentially of cellulose acetatepolymer plasticized with oxidizable plasticizer components which aredescribed hereiubelow. The amount of binder in the composition may vary,on

ord-

a weight basis, from about 15% to about 25%, variation within this rangebeing made to obtain well compacted and sturdy grains that do not deformunder the conditions of storage and handling described above. The amountof binder in the composition is preferably adjusted to obtainstoichiornetric balance with respect to oxygen content of thecomposition in order to produce a relatively smoke-free gas. 1 g

The cellulose acetate component of the binder is a partially esterifiedcellulose acetate having an acetic acid content between about 51 and 57%by weight. A particularly suitable cellulose acetate is the commerciallacquer grade marketed as having an acetic acid content of 54 to 56% byweight; usually spoken of as containing about 55% acetic acid. (The termpercent by weight acetic acid denotes the amount of acetic acid obtainedon saponification of the cellulose acetate.) The binder contains on aweight basis between about 20% and about 40% of cellulose acetatepolymer.

The dinitrotoluene component may be any one-ora mixture of thedinitrotoluenes having the two nitro groups attached to any two of thepositions of the phenyl-nucleus. The 2,4-dinitrotoluene isomer ispreferred. From about 10% to about 30% of dinitrotoluene is present inthe binder. v

The binder also contains dinitrophenoxyethanol, in relatively pure form,or a mixture of dinitrophenoxyeth- .anol with bis(dinitrophenoxy)ethanewhich mixture conaa'raase tains at least 50% of dinitrophenoxyethanoland preferably at least about 60% by Weight of the dinitrophenoxethanol.

The dinitrophenoxyethanol may be any one ofthe various isomeric species,but is preferably the 2,4-dinitrophenoxyethanol. The mixture is mosteasily obtained as the product in the common methods ofdinitrophenoxyethanol production. By control of the reaction conditionsutilized in these prior art methods, the reaction product may contain aslittle as 10 weight percent of the bis(dinitrophenoxy)ethane (secondaryreaction product) to as much as about 50 weight percent. The totalreaction product may require purification When it contains, as produced,more than this amount of a econdary reaction product.

Suitable mixtures may be readily prepared by the method taught byBlanksma and Fohr, Rec. trav. chim. 65, 711 (1946), whereindinitrochlorobenzene is reacted with ethylene glycol utilizing sodium asthe condensing agent; or by the method of Fairbourne and Toms, J. Chem.Soc. 119, 2077 (1921), wherein caustic soda is used as the condensingagent. To illustrate: the preferred plasticizer mixture is prepared byreacting 3.5 mols of ethylene glycol with 1 mol of2,4-dinitrochlorobenzene at a temperature in the range of about 80 to 95C. for a contact time of about 4 hours, in the presence of 50% aqueoussodium hydroxide solution; about 1 part by weight of sodium hydroxide isused for each 5 parts of the dinitrochlorobenzene. The solid reactionproduct is removed from the liquid by filtration, water washed and driedat moderate temperature. Under these conditions the reaction productconsists of about 63 weight percent of the primary reaction product,2,4-dinitrophenoxyethanol, and about 37 weight'percent of the secondaryreaction product, bis(2,4-dinitrophenoxy)ethane.

Several methods of analysis are available and it has been found that thecomposition of the'reaction product varies somewhat according to theanalytical technique. For example, when utilizing ditferentialsolubility procedure the amount of the secondary reaction product isalways greater than that found by direct analysis to determine theamount of 2,4-dinitrophenoxyethanol by acetylation, that is, bydetermination of the hydroxylnumber of the mixture. 1 If the mol ratioof ethylene glycol to 2,4-dinitrochlorobenzene is increased to about to1 the amount of bis(2,4-dinitrophenoxy)ethane is reduced to about 10% byWeight of the reaction product. The primary reaction product,dinitrophenoxyethanol, can be separated by difierential solubilityutilizing a boiling mixture of toluene or benzene to contact thereaction product. Relatively pure dinitrophenoxyethanol is recoveredfrom the aromatic solvent by concentrating the solution and 4 definitemelting point but liquifies over the temperature range of about 105 C.to 206 C.

The amount of the dinitrophenoxyethanol-containing component in thebinder may vary within the range of from about 10% to about 30% byweight of the binder. The amount of this material included in the binderwill vary Within this range depending upon the amount of otherplasticizer components in the binder and on the relative amounts ofdinitrophenoxyethanol and bis(dinitrophenoxy) ethane in the mixtures.

Usually the dinitrophenoxyethanol-containing component plus thedinitrotoluene component constitutesabout 40% by weight of the binder.When the mixture contains about 63% of 2,4-dinitrophenoxyethanol andabout 37% of bis(2,4-dinitrophenoxy)ethane, the binder preferablycontains about 20% of the mixture. When using 2,4-dinitrotoluene, thebinder preferably contains about 20% thereof.

Ethylene glycol diglycolate is a component of the binder. This materialis a polyester condensation reaction product having a molecular weightwithin the range of about 250 and about 1000. A molecular weight withinthe range of about 250 to about 600 is preferred. These low molecularWeights are obtained by using a mol excess of glycol to acid. The molratio of glycol to acid should bebetween about 1.02 and 1.3, preferablynot less than about 1.15 to obtain the most satisfactory condensationproduct with respect to plasticizer properties. This material isdescribed at length in the copending application of Norman]. Bowman andWayne A. Proe ll, entitled Polyester Plasticizer, filed November 30,1954, Serial No. 471,992, now abandoned.

The binder contains from about 25% to about 40% by weight of theethylene glycol diglycolate, preferably about 30%.

' The combustion catalyst of this invention may be either an inorganiccombustion catalyst or an organic catlayst. Examples of the inorganiccatalyst suitable for promoting the combustion of the propellant grainsare the Prussian blues, that is, the insoluble Prussian blue or solublePrussian blue, or chromates and dichromatessuch as ammonium dichromate,sodium chromate or. sodium dichromate. Mixtures of Prussian blues andammonium dichromate are particularly suitable for some uses. Thepreferred Prussian blue catalyst is insoluble Prussian blue. Themonoalkali metal salts of barbituric acid such as V monosodiumbarbiturate are suitable organic catalysts.

fractionally crystallizing the dinitrophenoxyethanol' from I thissolution. It is understood that considerable variation in the relativeproportions of the primary and secondary reaction products produced inthe product mixture may occur as a result of difierent methods ofproducing the dinitrophenoxyethanol-containing product and as a resultof difference in operating conditions such as washing the product, ratioof intermediates in the reaction mixture, temperature, etc. For example,in producing the 2,4-dimtro species, variation in product washingtechnique with respect to amount of water and temperature of the waterused for washing the product mixture may cause the relative amounts ofprimary and secondary reaction product to vary from about 60-65 parts byweight of primary reaction product to about 40-35 parts by weight of thesecondaryreaction product when using a 3.5 .to 1 ratio of The primaryreaction product, 2,4-dinit'rophenoxyethanol, melts at about 110 C. lThe bis(2,4-dinitrophenoxy)- ethane melts at about 206 C. The mixtureexhibits no The amount of catalyst used in the composition is betweenabout l% to about 10% based on the weight of the grain. Preferably theamount is within the range of from about 2% to about 6%.

When mixtures 'of- Prussian blue and ammonium dichromate are used theproportion by weight of the Prussian blue and ammonium dichromate is inthe range of about 0.5 to 2 parts by weightof Prussian blue per part byweight of ammonium dischomate.

The ammonium nitrate of this invention, which is the major component ofthe composition and which constitutes the remainder of the composition,may be ordinary commercial grade ammonium nitrate such as conventionallygrained ammonium nitrate containing a small amount of impurities. It maybe coated with a small amount of moisture-resisting material such aspetroleum or paraffin. Military grade ammonium nitrate and Cl. gradesuncoated are preferred. A mixture of finely ground and coarsely'groundammonium nitrate is preferred, the major portion of the nitrate beingfinely ground.

asraesa either from the channel blacks or the furnace blacks may beused. A second type of carbon which is adaptable for use as a combustionpromoter component is finely divided petroleum coke obtained in thepipe-stilling of midcontinent heavy residuums. Such coke usuallycontains less than 1% ash and hence, like the carbon blacks, isparticularly suitable in gas-producing compositions where it is desiredto keep to a minimum solid inorganic particles in the combustion gas.The coke is preferably ground to pass through a #325 US. standard sievebefore use. The amount of carbon which may be used in the composition iswithin the range of 0.3 to 2% by weight of the composition.

Ammonium nitrate solid propellants may require an inhibitor component toreduce the gassing tendency of the composition under high temperaturestorage conditions when using some catalysts or large amounts of anycatalyst. This gassing tendency may be avoided by the inclusion ofaromatic amines in the composition. Examples of aromatic amines whichare particularly efifective are the diaminotoluenes, diphenylamine,1,3-diaminobenzene, diamino naphthylenes, dinaphthyl amine,phenylnaphthyl amine and the triaminotoluenes. Particularly suitable arediphenyl amine and 2,4-diaminotoluene'. The amine may be added in anamount within the range of from about 0.5 to about 2% of the weight ofthe composition. The amount is determined by the gassing tendency of thecomposition in the absence of amine.

A minor amount of a surfactant may be added to the composition to obtainimproved contact of the components in mixing operations and in moldingof the compositions to shaped grains. A suitable surfactant is sorbitansesquioleate. The amount of surfactant is usually not more than about0.1% by weight of the composition. The gas-forming compositions of thisinvention may be prepared by: (1) making the binder, (2) mixing binderwith ammonium nitrate and other ingredients to form a homogeneous solidcomposition, (3) and molding the finished solid propellant grain. Thebinder is prepared by mixing heated cellulose acetate polymeric materialwith the plasticizer components in a suitable vessel. Mixing iscontinued until the mixture is completely plasticized. Blending of thebinder with ammonium nitrate and the other components of the formulationmay be carried out in the same mixer if desired. A mixing temperature of90lO5 C. affords a homogeneous somewhat dough-like solid. Mixing may becarried out under reduced pressure in order to remove adsorbed surfacemoisture present in the materials.

In another method of preparing the propellant corn- F position thebinder material is not prepared separately. In this method the drycomponents are first intimately mixed and the plasticizer is then addedto the admixed dry components. The ammonium nitrate and celluloseacetate are subjected to a temperature of about 110120 C. under about /3atmosphere pressure for a period of 30 to 60 minutes and the other drymaterials, such as solid binder components, catalyst, etc. areintimately mixed with the nitrate and acetate for an additional 15 to 30minutes under vacuum. The ethylene glycol diglycolate plasticizer isthen added along with surfactant, if any, and the final mixture isprepared by mixing for a period of 60 to 180 minutes to obtain ahomogeneous plasticized product, this final mixing being carried out atabout 105-1 15 C.

Burning rate test strips of the gas-forming composition are prepared byextruding or molding at a temperature below about 120 C. under apressure of about 2000 p.s.i. The strands are'coated with lacquer gradecellulose acetate on the sides to give strands which burn like acigarette and these are burned in a pressure bomb under nitrogenpressure. Four to six strands about Mr" x A" x 5" in length'are burnedat varying pressures between 600 and 1800 p.s.i. Plotting burning ratein inches per second against pressure on log-log paper KI: gives astraight line. The slope of this straight line is defined as theexponent of the burning rate related to pressure in the formula where Bis the linear burning rate at pressure p, p is the linear burning ratefor the composition at 1000 p.s.i., p is pressure in p.s.i. in theburning chamber and n is the pressure exponent showing dependence of theburning rate on pressure. This relationship of burning rate and pressureis discussed by R. N. Wimpress in Internal Ballistics of Solid FuelRockets (1950). A pressure exponent less than about 0.8 and preferablyless than about 0.7 is desirable for the ammonium nitrate propellantcomposition.

Gas-producing grains are prepared from the above compositions containingammonium nitrate, combustion promoter and binder material by moldingunder a pressure of about 2000 to 4000 p.s.i. The size and shape of thegrains are dependent upon their intended use. Grains are provided withcentrally located holes of different shapes, that is, starform,cruciform or circular. The gas-producing grains may be molded intodisc-form, stacks of discs being used as gas-forming propellant material for missile rockets.

The ends and cylindrical surface of the grains may be restricted withrespect to burning area by a coating of a material such as celluloseacetate or asphalt to limit burning to particular surfaces. 7

The test data obtained by burning the grains in the test motor indicateoverall performance of the compositions when used in assist take-offoperations. For these operations the grains are mounted in aconventional case provided'with a suitably placed igniter charge such ascannon powder, which is fired electrically. The temperature of the gasesproduced by burning of grains may be of the order of 1500 F. to 3400 F.but usually below about 2500 F. and the pressure or impulse produced bythe hot gases will be dependent upon the grain size, diameter of thenozzle, and other factors. 7

The grains are given a thermal shock test which is referred to as thecycling test. In this test, grains of a given composition are held in anoven at a temperature of 170 F. for a period of two hours, followingwhich they are immediately subjected for a period of two hours to atemperature of -75 F. in a refrigerator to complete one cycle. After asecond cycle, the grains are permitted to come to room temperature,i.e., about 75 to F. These grains are examined for indications ofcracking, crystallinity, and resistance to deformation and shatteringwhen dropped on a concrete surface. Grains are then fired at 75 F., F.and normal ambient temperatures following the cycling treatment. Grains,the binder of which consists of the plasticized cellulose acetateandplasticizer containing the'ethylene glycol diglycolate,dinitrotoluene and 2,4-dinitrophenoxyethanol-containing component ofthis invention show no physical defects following the thermal cyclingtest, and show firing qualities which are not affected by the cyclingtest. In another test the grains are dropped several feet to a concretesurface to test their mechanical strength. I

Another test to which finished grains are subjected is that of hotaging. In this test, grains are stored in an oven at 170 F. in thepresence of circulating air. Several grains of a given composition areused in such a test. Grains are withdrawn periodically and fired in atest motor. The best grains will not be affected after 30 days or moreof high temperature storage. A grain which will not tolerate prolongedhot storage malperforms ballistically. It may give an erratictime-pressure curve and may sometimes even burn with explosive violence.a

I 7 Example 1 A nitrophenoxyethanol binder component was pro test.

pared as follows. To a 70 gallon'stainless'steel kettle equipped withmotor operated stirrer and heating coils, was added 109 pounds ofethylene glycol and 102 pounds of technical grade2,4-dinitrochlorcbenzene to give a mol ratio of 3.5 to 1, ethyleneglycol to the dinitrochlorobenzene. The stirred mixture was heated to 65C. and a 50% aqueous solution of sodium hydroxide containing 22.7 poundsof caustic soda was added incrementally over a period of two hours. Theheat of reaction was sufiicient to maintain the temperature at 8095 C.without external heating. Following addition of the caustic solution themixture was stirred and the temperature was held at 8595 C. for anadditional two hours after which thirty gallons of water was addedslowly. The precipitated solid was filtered and the precipitate wasresuspended and washed in forty gallons of water, at a temperature of 6070 C. and filtered hot. The filter cake was washed repeatedly withgallon portions of warm water. Traces of sodium dinitrophenoxideresulting from partial hydrolysis of dinitrochlorobenzene were removedduring the washing operation. The product was air-dried 10 days atambient temperature. The yield of air-dried product containing less than1% moisture was 72.5 pounds of crude product. This crude productconsisted essentially of about 63 parts by weight of2,4-dinitrophenoxyethanol and 37 parts by weight ofbis(2,4-dinitrophenoxy ethane.

A mixture containing 32.5 parts by weight of lacquer grade celluloseacetate having an acetic acid content of about 55 weight percent; 14.8parts by weight of commer cial grade 2,4-dinitrotoluene; 26.6 parts byweight of 2,4 dinitrophenoxyethanol product containing about 63% byweight of the 2,4-dinitrophenoxyethanol and about 37% by weight ofbis(2,4-dinitrophenoxy)ethane; and 26.1 parts by weight of ethyleneglycol diglycolate was heated at a temperature in the range of l110 C.and mixed about one hour to obtain a homogeneous plasticized bindermaterial which was tough and flexible and showed good tear strength. Toa portion of this binder material was added diphenyl amine and a mixtureof insoluble Prussian blue and ammonium dichrornate catalyst containingthese catalyst components in equal amounts. Carbon black, finely groundammonium nitrate and a small amount of sorbitan sesquioleate were addedand mixing was continued to obtain a homogeneous gas-forming Vpropellant formulation which contained the'following components.

Ammonium nitrate Grains in the form of 2.75" cylinders 4" long andhaving a starform centrally located hole were prepared by molding theabove composition at 2400 psi. for 12 minutes. One of these grains wascycled in the thermal cycle test by subjecting it alternately totemperatures of 170 F. and 75 F. in two cycles as described hereinabove.Such cycling did not impair the physical structure of the grain whichgave normal firing properties following'the Another. 4" star grain gavesatisfactory firing performance in a rocket motor the gas produced beingsubstantially smoke-free. Still another 4" grain was dropped 6 feet to aconcrete floor and resisted fracture until the fourth drop from the 6.foot height. A burning strand prepared from the above composition showeda' burning 3 rate at 1000 psi; of0.118 inch per second and a pressureexponent of 0.58. 7

Example 2 A second composition'containing the same components as thecomposition of Example 1, but in dilferent proportions, was preparedaccording to the method described in tar grains of the same dimensionsas grains of Example .1 were molded at'2700 p.s.i. from the compositionof Example 2. Satisfactory rocket motor firings were obtained with thesegrains after being stored for 12, 20 and 31 days at 170 F. in the hotaging test. The gas produced upon firing these grains was substantiallysmoke-free. Additional like grains prepared from this composition werecycled successfully through the +170 No malformation of the F. and -75F. cycle test. grains, external or internal, was produced in the grainsin this severe cycle test. Strands of the composition btu'ned in anitrogen atmosphere in a pressure bomb at a rate of 0.134" per second at1000 p.s.i. The pressure exponent of the burning rate was 0.55.

Thus having described the invention what is claimed 1. A compositionsuitable for use as a solid propellant, which. composition consistsessentially of, on a weight basis (1) from about 15% to about of bindermaterial, which binder material consists, on a weight basis (a) about 20to about 40% of celluiose acetate containing from about 51% to about 57%of acetic acid, (b) about 10% to about of dinitrotoluene, (c) about 25%to'about of ethylene glycol diglycolate.

and (d) about 10% to about 30% of a member selected a from the classconsisting of dinitropheno-xyethancl and mixtures ofdinitrophenoxyethanol and bis(dinitrophenoxy)ethane, which mixturescontain at least 50 weight percent dinitrophenoxyethanol, (2) a catalystfrom the I (2,4-dinitrophenoxy)ethane.

is 2,4-dinitrophenoxyethanol. r

class consisting ofPrussion blue, ammonium dichromate, sodium chromate,sodium dichromate and monosodium barbiturate, in'an amount between about1 and l0percent by weight; and (3) the remainder essentially ammoniumnitrate.

2. The composition of claim 1 wherein said cellulose acetate containsabout 55 weight percent of acetic acid. 3. The composition of claim 1wherein said member is a mixture of about 63 parts by weightof2,4-dinitrophenoxyethanol and about 37 parts by weight of bis- 4. Thecomposition or" claim 1 wherein said member 5. The composition of claim1 wherein said catalyst is present in an amount between about 1%. andabout 10%. 6. The composition of claim 1 wherein said catalyst isPrussian blue,

7. The compoistion of claim 1' wherein said catalyst is ammoniumdichrornate. V I g I 8. T-he composition of claim l whereingsaidcatalyst is sodium barbiturate.

9. The eomposition ofjclaim l wherein said catalyst is a mixture ofPrussion blue and ammonium dichromate in the proportion by weight ofabout 0.5 to 2.

10. The composition of claim 1 containing from about 0.3% to about 2% offinely divided carbon.

11. The composition of claim 1 containing from about 0.5% to about 2% ofdiphenylamine.

12. A gas-producing composition consisting essentially, on a Weightbasis, of 1) from about 15 to about 25% of a binder said binderconsisting of (a) about 30% cellulose acetate material having an aceticacid content of 10 about 55 weight percent, (b) about 30% ethyleneglycol diglycolate, (0) about 20% 2,4-dinitrotoluene, and (d) about 20%of a mixture consisting of about 63% by weight 2,4-dinitrophenoxyethanoland about 37% by weight of bis(2,4-dinitrophenoxy)ethane; (2) from about15 References Cited in the file of this patent UNITED STATES PATENTS2,643,611 Ball June 30, 1953 FOREIGN PATENTS 655,585 Great Britain July21, 1951

1. A COMPOSITION SUITABLE FOR USE AS A SOLID PROPELLANT, WHICHCOMPOSITION CONSISTS ESSENTIALLY OF, ON A WEIGHT BASIS (1) FROM ABOUT15% TO ABOUT 25% OF BINDER MATERIAL, WHICH BINDER MATERIAL CONSISTS, ONA WEIGHT BASIS OF (A) ABOUT 20 TO ABOUT 40% OF CELLULOSE ACETATECONTAINING FROM ABOUT 51% TO ABOUT 57% OF ACETIC ACID, (B) ABOUT 10% TOABOUT 30% OF DINITROTOLUENE, (C) ABOUT 25% TO ABOUT 40% OF ETHYLENEGLYCOL DIGLYCOLATE, AND (D) ABOUT 10% TO ABOUT 30% OF A MEMBER SELECTEDFROM THE CLASS CONSISTING OF DINITROPHENOXYETHANOL AND MIXTURES OFDINITROPHENOXYETHANOL AND BIS(DINITROPHENOXY)ETHANE, WHICH MIXTURESCONTAIN AT LEAST 50 WEIGHT PERCENT DINITROPHENOXYETHANOL, (2) A CATALYSTFROM THE CLASS CONSISTING OF PRUSSION BLUE, AMMONIUM DICHROMATE, SODIUMCHROMATE, SODIUM DICHROMATE AND MONOSODIUM BARBITURATE, IN AN AMOUNTBETWEEN ABOUT 1 AND 10 PERCENT BY WEIGHT, AND (3) THE REMAINDERESSENTIALLY AMMONIUM NITRATE.